Generate config checks based on feature test macros.

Uses the C++ feature test macros to generate configuration checks in
both autoconf and CMake.

Makefile.am

@@ -1,5 +1,6 @@
 SUBDIRS = include src test tools config doc
-EXTRA_DIST = autogen.sh configitems README.md VERSION requirements.json
+EXTRA_DIST = \
+    autogen.sh configitems cxx_features.txt README.md VERSION requirements.json
 
 MAINTAINERCLEANFILES = \
     Makefile.in aclocal.m4 config.h.in config.log configure stamp-h.in

Makefile.in

@@ -95,6 +95,7 @@ am__aclocal_m4_deps = $(top_srcdir)/config/m4/libtool.m4 \
 	$(top_srcdir)/config/m4/ltsugar.m4 \
 	$(top_srcdir)/config/m4/ltversion.m4 \
 	$(top_srcdir)/config/m4/lt~obsolete.m4 \
+	$(top_srcdir)/pqxx_generated_checks.ac \
 	$(top_srcdir)/configure.ac
 am__configure_deps = $(am__aclocal_m4_deps) $(CONFIGURE_DEPENDENCIES) \
 	$(ACLOCAL_M4)
@@ -554,7 +555,9 @@ top_builddir = @top_builddir@
 top_srcdir = @top_srcdir@
 with_postgres_lib = @with_postgres_lib@
 SUBDIRS = include src test tools config doc
-EXTRA_DIST = autogen.sh configitems README.md VERSION requirements.json
+EXTRA_DIST = \
+    autogen.sh configitems cxx_features.txt README.md VERSION requirements.json
+
 MAINTAINERCLEANFILES = \
     Makefile.in aclocal.m4 config.h.in config.log configure stamp-h.in
 

autogen.sh

@@ -35,6 +35,7 @@ expand_templates $(find . -name \*.template)
 substitute include/pqxx/version.hxx.template >include/pqxx/version.hxx
 substitute include/pqxx/doc/mainpage.md.template >include/pqxx/doc/mainpage.md
 
+./tools/generate_cxx_checks.py
 
 autoheader
 libtoolize --force --automake --copy

cmake/config.cmake

@@ -116,6 +116,10 @@ try_compile(
 	${PROJECT_BINARY_DIR}
 	SOURCES ${PROJECT_SOURCE_DIR}/config-tests/cmp.cxx)
 
+# Incorporate feature checks based on C++ feature test macros.  The
+# generate_cxx_checks.py script produces these based on cxx_features.txt.
+include(pqxx_generated_checks)
+
 try_compile(
 	need_fslib
 	${PROJECT_BINARY_DIR}

cmake/pqxx_generated_checks.cmake

@@ -0,0 +1,35 @@
+try_compile(
+    PQXX_HAVE_CONCEPTS
+    ${PROJECT_BINARY_DIR}
+    SOURCES ${PROJECT_SOURCE_DIR}/config-tests/PQXX_HAVE_CONCEPTS.cxx
+)
+
+try_compile(
+    PQXX_HAVE_MULTIDIM
+    ${PROJECT_BINARY_DIR}
+    SOURCES ${PROJECT_SOURCE_DIR}/config-tests/PQXX_HAVE_MULTIDIM.cxx
+)
+
+try_compile(
+    PQXX_HAVE_SOURCE_LOCATION
+    ${PROJECT_BINARY_DIR}
+    SOURCES ${PROJECT_SOURCE_DIR}/config-tests/PQXX_HAVE_SOURCE_LOCATION.cxx
+)
+
+try_compile(
+    PQXX_HAVE_SPAN
+    ${PROJECT_BINARY_DIR}
+    SOURCES ${PROJECT_SOURCE_DIR}/config-tests/PQXX_HAVE_SPAN.cxx
+)
+
+try_compile(
+    PQXX_HAVE_SSIZE
+    ${PROJECT_BINARY_DIR}
+    SOURCES ${PROJECT_SOURCE_DIR}/config-tests/PQXX_HAVE_SSIZE.cxx
+)
+
+try_compile(
+    PQXX_HAVE_UNREACHABLE
+    ${PROJECT_BINARY_DIR}
+    SOURCES ${PROJECT_SOURCE_DIR}/config-tests/PQXX_HAVE_UNREACHABLE.cxx
+)

config-tests/PQXX_HAVE_CONCEPTS.cxx

@@ -0,0 +1,8 @@
+// Feature check for '__cpp_concepts'.
+// Generated by generate_cxx_checks.py at 2023-11-11 02:23:59.388992 UTC.
+#include <version>
+#if !defined(PQXX_HAVE_CONCEPTS) || !PQXX_HAVE_CONCEPTS
+#error "No support for __cpp_concepts detected."
+#endif
+
+int main() {}

config-tests/PQXX_HAVE_MULTIDIM.cxx

@@ -0,0 +1,8 @@
+// Feature check for '__cpp_multidimensional_subscript'.
+// Generated by generate_cxx_checks.py at 2023-11-11 02:23:59.389103 UTC.
+#include <version>
+#if !defined(PQXX_HAVE_MULTIDIM) || !PQXX_HAVE_MULTIDIM
+#error "No support for __cpp_multidimensional_subscript detected."
+#endif
+
+int main() {}

config-tests/PQXX_HAVE_SOURCE_LOCATION.cxx

@@ -0,0 +1,8 @@
+// Feature check for '__cpp_lib_source_location'.
+// Generated by generate_cxx_checks.py at 2023-11-11 02:23:59.389166 UTC.
+#include <version>
+#if !defined(PQXX_HAVE_SOURCE_LOCATION) || !PQXX_HAVE_SOURCE_LOCATION
+#error "No support for __cpp_lib_source_location detected."
+#endif
+
+int main() {}

config-tests/PQXX_HAVE_SPAN.cxx

@@ -0,0 +1,8 @@
+// Feature check for '__cpp_lib_span'.
+// Generated by generate_cxx_checks.py at 2023-11-11 02:23:59.389230 UTC.
+#include <version>
+#if !defined(PQXX_HAVE_SPAN) || !PQXX_HAVE_SPAN
+#error "No support for __cpp_lib_span detected."
+#endif
+
+int main() {}

config-tests/PQXX_HAVE_SSIZE.cxx

@@ -0,0 +1,8 @@
+// Feature check for '__cpp_lib_ssize'.
+// Generated by generate_cxx_checks.py at 2023-11-11 02:23:59.389294 UTC.
+#include <version>
+#if !defined(PQXX_HAVE_SSIZE) || !PQXX_HAVE_SSIZE
+#error "No support for __cpp_lib_ssize detected."
+#endif
+
+int main() {}

config-tests/PQXX_HAVE_UNREACHABLE.cxx

@@ -0,0 +1,8 @@
+// Feature check for '__cpp_lib_unreachable'.
+// Generated by generate_cxx_checks.py at 2023-11-11 02:23:59.389360 UTC.
+#include <version>
+#if !defined(PQXX_HAVE_UNREACHABLE) || !PQXX_HAVE_UNREACHABLE
+#error "No support for __cpp_lib_unreachable detected."
+#endif
+
+int main() {}

config/Makefile.in

@@ -94,6 +94,7 @@ am__aclocal_m4_deps = $(top_srcdir)/config/m4/libtool.m4 \
 	$(top_srcdir)/config/m4/ltsugar.m4 \
 	$(top_srcdir)/config/m4/ltversion.m4 \
 	$(top_srcdir)/config/m4/lt~obsolete.m4 \
+	$(top_srcdir)/pqxx_generated_checks.ac \
 	$(top_srcdir)/configure.ac
 am__configure_deps = $(am__aclocal_m4_deps) $(CONFIGURE_DEPENDENCIES) \
 	$(ACLOCAL_M4)

configitems

@@ -12,12 +12,16 @@ PQXX_HAVE_CXA_DEMANGLE	internal	compiler
 PQXX_HAVE_GCC_PURE	public	compiler
 PQXX_HAVE_GCC_VISIBILITY	public	compiler
 PQXX_HAVE_LIKELY	public	compiler
+PQXX_HAVE_MULTIDIM	public	compiler
 PQXX_HAVE_PATH	public	compiler
 PQXX_HAVE_POLL       internal        compiler
 PQXX_HAVE_SLEEP_FOR	internal	compiler
+PQXX_HAVE_SOURCE_LOCATION	public	compiler
 PQXX_HAVE_SPAN	public	compiler
+PQXX_HAVE_SSIZE	public	compiler
 PQXX_HAVE_STRERROR_R	public	compiler
 PQXX_HAVE_STRERROR_S	public	compiler
 PQXX_HAVE_THREAD_LOCAL       internal        compiler
+PQXX_HAVE_UNREACHABLE	public	compiler
 PQXX_HAVE_YEAR_MONTH_DAY	public	compiler
 VERSION	internal	autotools

configure

@@ -18174,6 +18174,220 @@ rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
 printf "%s\n" "$have_cmp" >&6; }
 
 
+# Incorporate feature checks based on C++ feature test macros.  The
+# generate_cxx_checks.py script produces these based on cxx_feaures.txt.
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking __cpp_concepts" >&5
+printf %s "checking __cpp_concepts... " >&6; }
+PQXX_HAVE_CONCEPTS=yes
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+// Feature check for '__cpp_concepts'.
+
+// Generated by generate_cxx_checks.py at 2023-11-11 02:23:59.388992 UTC.
+
+#include <version>
+
+#if !defined(PQXX_HAVE_CONCEPTS) || !PQXX_HAVE_CONCEPTS
+
+#error "No support for __cpp_concepts detected."
+
+#endif
+
+
+
+int main() {}
+
+
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"
+then :
+
+printf "%s\n" "#define PQXX_HAVE_CONCEPTS 1" >>confdefs.h
+
+else $as_nop
+  PQXX_HAVE_CONCEPTS=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $PQXX_HAVE_CONCEPTS" >&5
+printf "%s\n" "$PQXX_HAVE_CONCEPTS" >&6; }
+
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking __cpp_multidimensional_subscript" >&5
+printf %s "checking __cpp_multidimensional_subscript... " >&6; }
+PQXX_HAVE_MULTIDIM=yes
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+// Feature check for '__cpp_multidimensional_subscript'.
+
+// Generated by generate_cxx_checks.py at 2023-11-11 02:23:59.389103 UTC.
+
+#include <version>
+
+#if !defined(PQXX_HAVE_MULTIDIM) || !PQXX_HAVE_MULTIDIM
+
+#error "No support for __cpp_multidimensional_subscript detected."
+
+#endif
+
+
+
+int main() {}
+
+
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"
+then :
+
+printf "%s\n" "#define PQXX_HAVE_MULTIDIM 1" >>confdefs.h
+
+else $as_nop
+  PQXX_HAVE_MULTIDIM=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $PQXX_HAVE_MULTIDIM" >&5
+printf "%s\n" "$PQXX_HAVE_MULTIDIM" >&6; }
+
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking __cpp_lib_source_location" >&5
+printf %s "checking __cpp_lib_source_location... " >&6; }
+PQXX_HAVE_SOURCE_LOCATION=yes
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+// Feature check for '__cpp_lib_source_location'.
+
+// Generated by generate_cxx_checks.py at 2023-11-11 02:23:59.389166 UTC.
+
+#include <version>
+
+#if !defined(PQXX_HAVE_SOURCE_LOCATION) || !PQXX_HAVE_SOURCE_LOCATION
+
+#error "No support for __cpp_lib_source_location detected."
+
+#endif
+
+
+
+int main() {}
+
+
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"
+then :
+
+printf "%s\n" "#define PQXX_HAVE_SOURCE_LOCATION 1" >>confdefs.h
+
+else $as_nop
+  PQXX_HAVE_SOURCE_LOCATION=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $PQXX_HAVE_SOURCE_LOCATION" >&5
+printf "%s\n" "$PQXX_HAVE_SOURCE_LOCATION" >&6; }
+
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking __cpp_lib_span" >&5
+printf %s "checking __cpp_lib_span... " >&6; }
+PQXX_HAVE_SPAN=yes
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+// Feature check for '__cpp_lib_span'.
+
+// Generated by generate_cxx_checks.py at 2023-11-11 02:23:59.389230 UTC.
+
+#include <version>
+
+#if !defined(PQXX_HAVE_SPAN) || !PQXX_HAVE_SPAN
+
+#error "No support for __cpp_lib_span detected."
+
+#endif
+
+
+
+int main() {}
+
+
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"
+then :
+
+printf "%s\n" "#define PQXX_HAVE_SPAN 1" >>confdefs.h
+
+else $as_nop
+  PQXX_HAVE_SPAN=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $PQXX_HAVE_SPAN" >&5
+printf "%s\n" "$PQXX_HAVE_SPAN" >&6; }
+
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking __cpp_lib_ssize" >&5
+printf %s "checking __cpp_lib_ssize... " >&6; }
+PQXX_HAVE_SSIZE=yes
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+// Feature check for '__cpp_lib_ssize'.
+
+// Generated by generate_cxx_checks.py at 2023-11-11 02:23:59.389294 UTC.
+
+#include <version>
+
+#if !defined(PQXX_HAVE_SSIZE) || !PQXX_HAVE_SSIZE
+
+#error "No support for __cpp_lib_ssize detected."
+
+#endif
+
+
+
+int main() {}
+
+
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"
+then :
+
+printf "%s\n" "#define PQXX_HAVE_SSIZE 1" >>confdefs.h
+
+else $as_nop
+  PQXX_HAVE_SSIZE=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $PQXX_HAVE_SSIZE" >&5
+printf "%s\n" "$PQXX_HAVE_SSIZE" >&6; }
+
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking __cpp_lib_unreachable" >&5
+printf %s "checking __cpp_lib_unreachable... " >&6; }
+PQXX_HAVE_UNREACHABLE=yes
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+// Feature check for '__cpp_lib_unreachable'.
+
+// Generated by generate_cxx_checks.py at 2023-11-11 02:23:59.389360 UTC.
+
+#include <version>
+
+#if !defined(PQXX_HAVE_UNREACHABLE) || !PQXX_HAVE_UNREACHABLE
+
+#error "No support for __cpp_lib_unreachable detected."
+
+#endif
+
+
+
+int main() {}
+
+
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"
+then :
+
+printf "%s\n" "#define PQXX_HAVE_UNREACHABLE 1" >>confdefs.h
+
+else $as_nop
+  PQXX_HAVE_UNREACHABLE=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $PQXX_HAVE_UNREACHABLE" >&5
+printf "%s\n" "$PQXX_HAVE_UNREACHABLE" >&6; }
+
+
+
 # Doing my own check for poll().  There's one built into autoconf-archive, but
 # it produces warnings in C++ (about unnecessarily using "struct", and using 0
 # as a null pointer constant).  In maintainer mode, those warnings turn into

configure.ac

@@ -439,6 +439,11 @@ AC_COMPILE_IFELSE(
 AC_MSG_RESULT($have_cmp)
 
 
+# Incorporate feature checks based on C++ feature test macros.  The
+# generate_cxx_checks.py script produces these based on cxx_feaures.txt.
+m4_include([pqxx_generated_checks.ac])
+
+
 # Doing my own check for poll().  There's one built into autoconf-archive, but
 # it produces warnings in C++ (about unnecessarily using "struct", and using 0
 # as a null pointer constant).  In maintainer mode, those warnings turn into